fuse: add support for mandatory locking

For mandatory locking the userspace filesystem needs to know the lock
ownership for read, write and truncate operations.

This patch adds the necessary fields to the protocol.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 36 insertions, 8 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 052327b..6c83ed0 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1108,6 +1108,11 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 		inarg.valid |= FATTR_FH;
 		inarg.fh = ff->fh;
 	}
+	if (attr->ia_valid & ATTR_SIZE) {
+		/* For mandatory locking in truncate */
+		inarg.valid |= FATTR_LOCKOWNER;
+		inarg.lock_owner = fuse_lock_owner_id(fc, current->files);
+	}
 	req->in.h.opcode = FUSE_SETATTR;
 	req->in.h.nodeid = get_node_id(inode);
 	req->in.numargs = 1;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 2b589de..0fcdba9 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -189,7 +189,7 @@ static int fuse_release(struct inode *inode, struct file *file)
  * Scramble the ID space with XTEA, so that the value of the files_struct
  * pointer is not exposed to userspace.
  */
-static u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
+u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 {
 	u32 *k = fc->scramble_key;
 	u64 v = (unsigned long) id;
@@ -308,11 +308,19 @@ void fuse_read_fill(struct fuse_req *req, struct fuse_file *ff,
 }
 
 static size_t fuse_send_read(struct fuse_req *req, struct file *file,
-			     struct inode *inode, loff_t pos, size_t count)
+			     struct inode *inode, loff_t pos, size_t count,
+			     fl_owner_t owner)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_file *ff = file->private_data;
+
 	fuse_read_fill(req, ff, inode, pos, count, FUSE_READ);
+	if (owner != NULL) {
+		struct fuse_read_in *inarg = &req->misc.read_in;
+
+		inarg->read_flags |= FUSE_READ_LOCKOWNER;
+		inarg->lock_owner = fuse_lock_owner_id(fc, owner);
+	}
 	request_send(fc, req);
 	return req->out.args[0].size;
 }
@@ -336,7 +344,8 @@ static int fuse_readpage(struct file *file, struct page *page)
 	req->out.page_zeroing = 1;
 	req->num_pages = 1;
 	req->pages[0] = page;
-	fuse_send_read(req, file, inode, page_offset(page), PAGE_CACHE_SIZE);
+	fuse_send_read(req, file, inode, page_offset(page), PAGE_CACHE_SIZE,
+		       NULL);
 	err = req->out.h.error;
 	fuse_put_request(fc, req);
 	if (!err)
@@ -447,6 +456,7 @@ static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
 			    struct inode *inode, loff_t pos, size_t count,
 			    int writepage)
 {
+	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_write_in *inarg = &req->misc.write.in;
 	struct fuse_write_out *outarg = &req->misc.write.out;
 
@@ -459,7 +469,10 @@ static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
 	req->in.h.nodeid = get_node_id(inode);
 	req->in.argpages = 1;
 	req->in.numargs = 2;
-	req->in.args[0].size = sizeof(struct fuse_write_in);
+	if (fc->minor < 9)
+		req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
+	else
+		req->in.args[0].size = sizeof(struct fuse_write_in);
 	req->in.args[0].value = inarg;
 	req->in.args[1].size = count;
 	req->out.numargs = 1;
@@ -468,10 +481,16 @@ static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
 }
 
 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
-			      struct inode *inode, loff_t pos, size_t count)
+			      struct inode *inode, loff_t pos, size_t count,
+			      fl_owner_t owner)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	fuse_write_fill(req, file->private_data, inode, pos, count, 0);
+	if (owner != NULL) {
+		struct fuse_write_in *inarg = &req->misc.write.in;
+		inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
+		inarg->lock_owner = fuse_lock_owner_id(fc, owner);
+	}
 	request_send(fc, req);
 	return req->misc.write.out.size;
 }
@@ -508,7 +527,7 @@ static int fuse_buffered_write(struct file *file, struct inode *inode,
 	req->num_pages = 1;
 	req->pages[0] = page;
 	req->page_offset = offset;
-	nres = fuse_send_write(req, file, inode, pos, count);
+	nres = fuse_send_write(req, file, inode, pos, count, NULL);
 	err = req->out.h.error;
 	fuse_put_request(fc, req);
 	if (!err && !nres)
@@ -609,9 +628,11 @@ static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 		nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 		nbytes = min(count, nbytes);
 		if (write)
-			nres = fuse_send_write(req, file, inode, pos, nbytes);
+			nres = fuse_send_write(req, file, inode, pos, nbytes,
+					       current->files);
 		else
-			nres = fuse_send_read(req, file, inode, pos, nbytes);
+			nres = fuse_send_read(req, file, inode, pos, nbytes,
+					      current->files);
 		fuse_release_user_pages(req, !write);
 		if (req->out.h.error) {
 			if (!res)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 8b64a63..6c5461d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -591,3 +591,5 @@ int fuse_valid_type(int m);
  * Is task allowed to perform filesystem operation?
  */
 int fuse_allow_task(struct fuse_conn *fc, struct task_struct *task);
+
+u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);